In order to deliver effective patient treatment, radiation treatment systems require that the patient be properly positioned in relation to the system that is to deliver the treatment. Current treatment delivery systems utilize algorithms that automatically align a treatment couch to properly position a patient relative to the treatment delivery system. However, because some algorithms may only be capable of making fine adjustments to the position of the patient, the initial position of the treatment couch (and the patient) is often so out of alignment with the imaging center that it prevents the algorithm from returning a useful result. In these cases, a user of the treatment delivery system must manually adjust the position of the couch to more closely align with the imaging center. In order to accomplish this, current solutions acquire a pair of initial projection images of the patient and display them in conjunction with a corresponding pair of synthetic projection images. The user then adjusts the position of the projection images to overlay the synthetic projection images, and the system moves the treatment couch accordingly. By doing this, the patient is eventually moved close enough to a position that allows the algorithm to properly detect the position of the patient in relation to the imaging center.
FIG. 1 illustrates a user interface 100 for adjusting the position of a projection image that is currently used in the CyberKnife® radiosurgery system, developed by Accuray, Incorporated of California. The user interface 100 includes three sliders 104 to allow the user to move projection images 102 relative to the synthetic projection images 106. The position of each projection image relative to the synthetic projection images can be seen in overlay windows 108. Changing the position of one of the sliders 104 simulates a change in the position of the treatment couch in a particular direction relative to anatomical coordinates of the human body (inferior/superior, left/right, and anterior/posterior, respectively). This change is reflected in a shift in the position of the projection images in overlay windows 108. Because the displayed projection images are two dimensional projections of a three dimensional figure, the user must identify how the projection images will respond to movements of the sliders, which allow for movements in three directions.